Implement Circuit Breakers for Resilient External Service Calls

use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;

class CircuitBreaker
{
    private $failureThreshold = 3;
    private $resetTimeout = 30;
    private $lastFailureTime;
    private $failureCount = 0;

    public function call(callable $function)
    {
        if ($this->isOpen()) {
            throw new Exception('Circuit is open');
        }

        try {
            $result = $function();
            $this->reset();
            return $result;
        } catch (Exception $e) {
            $this->recordFailure();
            throw $e;
        }
    }

    private function isOpen()
    {
        if ($this->failureCount >= $this->failureThreshold) {
            $timeSinceLastFailure = time() - $this->lastFailureTime;
            if ($timeSinceLastFailure <= $this->resetTimeout) {
                return true;
            }
            $this->reset();
        }
        return false;
    }

    private function recordFailure()
    {
        $this->failureCount++;
        $this->lastFailureTime = time();
    }

    private function reset()
    {
        $this->failureCount = 0;
        $this->lastFailureTime = null;
    }
}

// Usage
$circuitBreaker = new CircuitBreaker();
try {
    $result = $circuitBreaker->call(function() {
        $client = new Client();
        return $client->get('http://api.example.com');
    });
} catch (Exception $e) {
    // Handle the exception
}